Catalyst Assessment

CATALYST ASSESSMENT

DCL carefully considers all mechanisms involved in catalyst deterioration, to ensure the long-term performance of target emissions. DCL maintains a large database of model gas, test cell, and in-field catalyst aging data.

IDEAL SURFACE

Good adhesion

Well-dispersed particles

Similar thermal expansion coefficients of substrate and washcoat

CHEMICAL DETERIORATION

Poisoning; irreversible adsorption or reaction on/with the surface

Inhibition; competitive reversible

adsorption of the poison precursors

> Sulphur poisoning reversible at greater than 600^oC / 1110^oF, caused by ZDDP (zinc dialkyl dithio phosphate)

> Lube oil poisoning by phosphorus additives (irreversible)

THERMAL DETERIORATION

Sintering (re-dispersion)

Alloying

Support changes

Noble metal-base metal interactions

> High-temperature sintering

> Complete collapse of washcoat

> Loss of surface area from 200m²/g to 5m²/g at 1200^oC/2200^oF

FOULING

Carbonaceous deposits (coking)

> Soot and ash deposits, reversible by catalyst washing/cleaning

MECHANICAL DETERIORATION

Thermal shock

Attrition/erosion

Physical breakage